High temperature butterfly valve seal

Author:butterfly Valve     Published time:2019-07-22 09:00     Reading times:106    

The sealing performance of the china valve refers to the ability of the valve sealing pair to prevent leakage of the medium, and is an important technical performance index of the valve. China butterfly valve sealing technology is constantly evolving. The double eccentric butterfly valve is a force applied between the valve seat and the butterfly plate by the valve stem, and a certain elastic deformation is generated between the sealing pairs to achieve sealing. Two sealing faces, one tapered sealing face and the other is a circular sealing face, so the double eccentricity is a wire seal.

The triple eccentric butterfly valve is based on the double eccentric butterfly valve. The center of the double eccentric valve stem is centered, and the conical sealing surface is deflected by a certain angle. At this time, the sealing surface of the three eccentric butterfly valve is no longer a circular line seal, but an elliptical surface. Sealed, the sealing surface shape is asymmetrical. In order to prevent the butterfly valve from being excessively closed, the sealing surface of the small piece portion is parallel to the valve flow path. Therefore, the triple eccentric butterfly valve fundamentally changes the design structure of the butterfly valve.

When the butterfly valve is closed, the sealing of the small eccentric butterfly valve is achieved by the valve stem pressure. In the periphery of the elliptical slanted cone butterfly plate of the three eccentric butterfly valve, a sealing ring formed by superimposing a stainless steel plate and a flexible graphite is embedded. This type of sealing has the double advantages of a metal hard seal and a non-metal soft seal, and the sealing performance index Higher. When the butterfly valve is working in ultra-high temperature or ultra-low temperature conditions, the temperature change will cause the seal to be deformed. If the deformation is not effectively controlled and compensated, the seal pair will have a gap, which will cause leakage. Therefore, under normal conditions, butterfly valves are not suitable for use in ultra-high temperature or ultra-low temperature conditions.

In order to broaden the application range of the butterfly valve, the sealing structure design of the butterfly valve is started. By using the elastic sealing pair or the ability to improve the elastic deformation of the sealing pair, the deformation caused by the temperature change between the valve sealing pairs is compensated or filled, and the butterfly valve is ensured in the ultra-high temperature work. Reliable seal under conditions.